Worcester Heatslve 15/19 bleed problem!

[yanc]

Hi, I drained down the system and changed a radiator at the w/e. The system is now re-pressurised but when I try to run the boiler it shuts down after 5mins. The inlet pipe to the pump is very hot as is the pump but the outlet pipe to the diverter valve is cold. The pump seems to be running ok as you can hear it and it changes speed when the speed control swt is moved, but it seems its not pumping any water. Could it be air in the pump still or maybe the impellor has broken? Tried using the chrome screw in the centre of the pump to bleed it to no effect. Are there any ways of bleeding it?

The burner is working fine and there is no lockout.

Any help would be most appreciated
Thanks

 

[Burnerman]

Lift the top off the boiler - there are 3 bleed points up there, plus the auto air vent....that should get you away!
John

 

[yanc]

Thanks for the reply.

Is it normal to have to bleed these three after a drain dow and are they easy to see? I assume they just look a like anormal radiator bleed screw? Do my symptoms sound like air in the system?

Cheers...

 

[Burnerman]

Any air in the pipes on the top of the boiler need to be vented, and they are normal rad bleed valve square type. One is at the back, one just after the dhw heat exchanger and the other close to the expansion vessel. The automatic air valve has a car tyre type valve cap on the top, so open that to see what comes out.
Obviously the pump could have failed, and the usual test is to remove the centre chrome screw and by putting a small screwdriver through the hole, you can feel the impeller running.
John

 

[yanc]

Hi John,

Thanks for your help, all seems to be working fine.

I bled all three rad type screws and that did the trick. Wasnt sure about the auto air vent as there are two schrader valves, one on the red exp tank and another on a brass unit. How come when you remove the chrome screw on the pump you dont get mains pressure water, thought you could only remove this when there was no pressure? I did remove it and just had a trickle of water come out. Is it a good idea to put a screwdriver in the hole, could you not damage the impellor? Assume you have to flick the pwr on and some water will come out of the hole as it spins up?

Thanks...

 

[Burnerman]

Just for your info - the schrader valve on the expansion vessel is for topping up with air....the system needs to be completely depressurised water wise and then air to 10 psi is pumped into the EV with a car foot pump or similar. If you depress this valve, and water hits you in the eye then the EV is goosed.
The automatic air vent (brass unit) has a similar cap on it, so just undo it and let any air out.
Regarding the circulating pump, you can take the chrome screw right out - there will be a few drips of water but no flood. A small electricians screwdriver is poked through the hole to engage on the end of the impeller to give it a twirl if its stuck.
Pleased you are sorted!
John